Topic 5 Flashcards
What is asexual reproduction?
A process resulting in the production of genetically identical offspring from one parent.
- No fusion of gametes: no mixing of genetic information
- Produces clones
- No genetic variation
What examples of organisms asexually reproduce?
Bacteria, fungi, small plants, animals, potatoes, bulbs.
What are 2 advantages of asexual reproduction?
- Faster
- Less energy required
What is the disadvantage of asexual reproduction?
Offspring are all genetically identical - doesn’t produce genetic variation.
What is mitosis?
Nucleas division giving rise to genetically identical cells
What is sexual reproduction?
A process involving the fusion of the nuclei of two
How does asexual reproduction occur?
Mitosis.
What is mitosis?
Nuclear division giving rise to genetically identical cells.
What happens during the process of mitosis?
During mitosis the DNA/chromosome replicates, then the cell divides. Half of the chromosomes will move into each divided cell, creating the two daughter cells with the same number of chromosomes as the parent cell.
What is sexual reproduction?
The process involving the fusion of the nuclei of two gametes to form a zygote and the production of offspring that are genetically different from each other.
What is fertilisation?
The fusion of the nuclei of gametes.
What are the features of the nuclei of gametes and nucleus of zygote?
Gamete = haploid
Zygote = diploid
What is meiosis used for and what does it produce?
Used for making gametes. Produces 4 haploid daughter cells with half the chromosome number of a regular body cell (diploid).
Why is meiosis important for reproducing?
So the offspring will have a diploid number of chromosomes.
Advantage of genetic variation in the wild:
Genetic variation means that organisms can better survive changes in the environment. Some individuals may die, but as the population is genetically diverse, some will have traits to survive.
Advantage of genetic variation in crops:
Having crop plants that are genetically different to one another is important for ensuring the crop can survive environmental change.
What is the carpel? What does it consist of?
The female part of the flower. Consists of the stigma, style and ovary.
What is the stamen?? What does it consist of?
The male part of the flower. Consists of the anther and filament.
What does the filament do?
The filament elevates anther exposing it to wind and pollinators.
What does the anther do?
Contains and releases pollen (male gamete)
What does the ovule/ovary do in plants?
Produces ovule (female gametes)
What does the style do?
Elevates stigma, exposing it to wind and pollinators. Connects the stigma to ovary)
What does the stigma do?
Catches pollen from wind and pollinators. (Sticky opening)
What does the sepal do?
Thick protective leaves on outside of bud, peel back after blooms.
What does the receptacle do?
Connects stem to flower.
What does the petal do?
Attract pollinators - vibrant colors.
What is the difference between ovule and ovary?
Ovary contains the ovules.
What are 5 features of wind pollinated plants?
- No showy petals
- No odor
- Lots of pollen. Dry (not sticky), small, light, aerodynamic
- Stigma is feathery and sticky. Hangs out of the flower
- Anther dangles loosely on long filaments move freely in the wind.
5 features of insect pollinated plants?
- Petals: large and showy colors
- Delicate and sweet (attractive) odors
- Pollen is sticky/patterned. Small amounts produced
- Stigma is small and sticky inside the flower
- Less anthers inside the flower
What is pollination?
The transfer of pollen grains from an anther to a stigma.
What is self-pollination?
The transfer of pollen grains from the anther of a flower to the stigma of the same flower or a different flower on the same plant.
What is cross-pollination?
The transfer of pollen grains from the anther of a flower to the stigma of a flower on a different plant of the same species.
4 potential effects of self pollination:
- Risk in homozygosity (less genetic diversity)
- Lack of variation
- Inbreeding depression - recessive mutations
- Consistency in the offspring
What is an effect of cross pollination on plants?
Has the potential to produce healthier plants. This method increases plant species genetic variety.
What patterns do bee pollinated plants tend to show?
Purple, yellow or white with bullseyes coloration.
Do bird pollinated flower have scent?
No.
What does the prostate gland do
Produces fluid called semen that provide sperm cells with nutrients
What does the sperm duct do
Sperm passes through the sperm duct to be mixed with fluids produced by the glands before being passed into the urethra for ejaculation
What does urethra do
Tube running down the centre of the penis that can carry out urine or semen, a ring of muscle in the urethra prevents the urine and semen from mixing
What does testis do
Contained within a bag of skin (scrotum) and produces sperm (male gamete) and testosterone hormone
What does scrotum do
Sac supporting the testes outside the body to ensure that sperm are kept at a temperature slightly lower than body temperature
What does penis do
Passes urine out of the body from the bladder and allows semen to pass into the vagina of a woman during sexual intercourse
What does oviduct do
Connects the ovary to the uterus and is lined with ciliated cells to push the released ovum down it. Fertilisation occurs here
What does ovary do
Contains ova (female gametes) which will mature and develop when hormones are released
What does uterus do
Muscular bag with a soft lining where the fertilised egg (zygote) will be implanted to develop into a foetus
What does cervix do
Ring of muscle at the lower end of the uterus to keep the developing foetus in place during pregnancy
Function of flagellum: sperm
allows the sperm to swim towards the egg
Function of enzymes in head region (acrosome): sperm
To digest a route into the egg for fertilisation
Function of many mitochondria: sperm
To provide energy for movement of the flagellum
Function of cytoplasm containing store of energy: egg
To provide energy for cell division in the developing zygote after fertilisation
Function of jelly-like coating: egg
to make an impenetrable barrier after fertilisation to prevent more sperm entering the egg
How long does it take for zygote to travel to uterus
3 days
What is implantation
Embryo embeds itself in the thick lining of uterus and continues to grow and develop
What happens to fetus in first 12 weeks
Major development of organs, nutrients gained from mother by diffusion through uterus lining. Placenta formed
What is fetus surrounded by
Amniotic sac, containing amniotic fluid (made from mother’s blood plasma) - protects fetus by cushioning it from bumps to the mother’s abdomen
What does umbilical cord do
Fetus blood supply for exchange of nutrients, removal of waste products
What is needed during gestation period (9 months)
Glucose, amino acids, fats, water, oxygen
How is placenta adapted for diffusion
Large surface area, thin wall
Why are preganant women advised not to smoke
Some pathogenic organisms cannot pass through placenta (acts as barrier) however nicotine can pass through
What does fetus blood connect to
From placenta by umbilical cord
What absorbs waste from fetus
Mothers blood, absorbs CO2, urea
How does movement of molecules occur over placenta
Diffusion, due to difference in concentration gradients
What is ovulation
Release of an egg, occurs halfway through the cycle (day 14) and egg travels down the oviduct to the uterus
When does menstruation occur
Failure to fertilise egg - breakdown of the thickened lining of the uterus
What is menstrual cycled controlled by
Hormones released from ovary and pituitary gland
What does FSH do (follicle-stimulating hormone)
- stimulates egg maturation in the follicles of the ovary
- stimulates follicles in the ovaries to secrete oestrogen
What does LH do (luteinizing hormone)
- at its peak stimulates ovulations (release of egg)
- results in the formation of corpus luteum (temporary collection of cells that form on your ovary)
Oestrogen during menstrual cycle
- stimulates the uterus to develop a lining (replace lining lost due to menstruation)
- post-ovulation, inhibits FSH and LH production in the pituitary gland
Progesterone during menstrual cycle
- maintains and thickens lining of the uterus
- inhibhits FSH and LH production
- if fertilisation doesn’t occur, levels drop and menstruation occurs
Describe all 4 hormones interacting during menstrual cycle
- Pituitary gland produces FSH, stimulating development of a follicle in ovary
- Egg develops in follicle and follicle produces OESTROGEN
- OESTROGEN causes growth and repair of the linign of uterus wall and inhibits FSH
- When oestrogen rises to a high enough level, stimulates the release of LH from pituitary gland, causing ovulation
- Follicle becomes corpus luteum and starts producing PROGESTERONE
- PROGESTERONE maintains uterus lining
- If egg not fertilised, corpus luteum breaks down and PROGESTERONE levels drop
- This causes mensturation (uterus linign breaks down)
What happens to corpus lutem if you are pregnant
Continues to produce progesterone, preventing uterus lining from breaking down and aborting the pregnancy
What hormone can placenta secrete
Progesterone (corpus leutum stops when placent secretes it)
How does HIV affect immune system
- mild flu-like symptom after infection
- virus infects a certain type of lymphocyte of the body’s immune system
- HIV avoids being recognised and destroyed by changing its protein coat
- infects certain type of lymphocyte and uses cells machinery to multiply
- reduces number of lymphocytes, therefore amount of anibodies that can be made
- Decreases body’s ability to fight off infections eventually leading to AIDS (Acquired Immunodeficiency)
How to control spread of STI’s
- limiting number of sexual partners an individual has
- use condom
- get tested
- education programmes
